Gene therapy for renal anemia in mice with polycystic kidney using an adenovirus vector encoding the human erythropoietin gene

BACKGROUND

Recombinant human erythropoietin (rHuEPO) is primarily used for patients with anemia associated with end-stage renal disease. We evaluated the efficacy of EPO gene therapy using adenovirus vector for chronic renal failure mice expressing severe renal anemia.

METHODS

Recombinant HuEPO gene transfer to mesothelial cells was performed in vitro and in vivo. Recombinant replication-deficient adenoviruses containing rHuEPO cDNA (AdCMVEPO), E. coli lacZ gene (AdCMVlacZ), or an nonexogenous gene (AdNull as control vector) driven by the cytomegalovirus promotor/enhancer were constructed. The oligosaccharides associated with the rHuEPO from AdCMVEPO-treated mesothelial cells were analyzed. For in vivo study, the DBA/2FG-pcy mouse, a model for human autosomal recessive polycystic kidney disease resulting in chronic renal failure with progressive anemia, was used.

RESULTS

The sialylated oligosaccharides associated with the rHuEPO produced in AdCMVEPO-treated mesothelial cells occupied 78 +/- 0.7% of the total oligosaccharide pool. A single intraperitoneal administration of AdCMVEPO induced rHuEPO synthesis in the peritoneal cells and a marked increase in erythrocyte production. The maximal increase in hematocrit (43 +/- 4%) was observed on day 28, and it remained elevated for 40 days.

CONCLUSION

These results indicate that intraperitoneal administration of AdCMVEPO improves renal anemia in mice with chronic renal failure and that the mesothelial cell is an appropriate target cell for gene transfer.

Exacerbation of systemic lupus erythematosus related to cytomegalovirus infection

We report two patients with systemic lupus erythematosus (SLE) in whom cytomegalovirus (CMV) infection may have played a significant role in the exacerbation or onset of symptoms. The first patient had thrombocytopenia and the second had proteinuria. CMV infection was observed in both patients when their symptoms developed.

Follow-up study on urinary type IV collagen in patients with early stage diabetic nephropathy

Type IV collagen is a major component released from the glomerular and tubular basement membranes. To investigate the alteration of renal type IV collagen turnover in early stage diabetic nephropathy, urinary type IV collagen was measured by a highly sensitive one-step sandwich enzyme immunoassay (EIA). Urinary samples were obtained from 94 diabetic patients without overt proteinuria. Among those patients, 61 were normoalbuminuric and 33 patients were in the microalbuminuric group. Levels of urinary type IV collagen were serially examined at the start of this study and again one year later. The levels of urinary type IV collagen in patients in the microalbuminuric group were significantly higher than those in the normoalbuminuric group (P < 0.01). There was a significant correlation between the concentration of urinary albumin and urinary type IV collagen in both groups (P < 0.05). Twenty-eight patients (45.3%) in the normoalbuminuric group who showed an abnormal elevation of urinary type IV collagen in comparison to the reference range of normal healthy adults (normal range; less than 3.5 microg/g x Cr). Seven (25%) out of these 28 normoalbuminuric patients with increased urinary type IV collagen progressed to the microalbuminuric group one year later. The levels of urinary type IV collagen in such patients were significantly increased. In the 21 patients who stayed within the normoalbuminuric group, the urinary type IV collagen levels were significantly decreased one year later. It appears that the levels of urinary type IV collagen might reflect ongoing alteration of the extracellular matrix (ECM) turnover and might define more specifically the early stage diabetic nephropathy than the detection of microalbuminuria. It is concluded that the serial measurement of urinary type IV collagen can be a useful marker for detecting renal injury in diabetes.

Urinary levels of monocyte chemoattractant protein (MCP)-1 and disease activity in patients with IgA nephropathy

Using a quantitative sandwich ELISA, we studied 17 patients with IgA nephropathy to determine if levels of urinary monocyte chemoattractant protein-1 (MCP-1) might reflect the disease activity. The levels of urinary MCP-1 in patients with the advanced stage were significantly higher than those in patients with the mild stage of the disease, or in healthy controls. The results showed a significant correlation between the levels of urinary MCP-1 and the disease activity, i.e., levels of urinary casts and urinary protein. It was thus suggested that the measurement of urinary MCP-1 is useful in evaluating the degree of renal injuries and/or prognosis in patients with IgA nephropathy.

Effects of treatment with angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor antagonist (AIIRA) on renal function and glomerular injury in subtotal nephrectomized rats

The aim of this study was to determine if treatment with angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II receptor antagonists (AIIRA) might decrease urinary albumin excretion and prevent glomerular enlargement and glomerulosclerosis in subtotal (5/6) nephrectomized rats. Morphometric image analysis of glomeruli was also performed in the subtotal nephrectomized rats. The nephrectomized rats were treated with ACEI (enalapril 100 mg/l), AIIRA (L-158,809 10 mg/l) or TRX (reserpine 5 mg/ l, hydralazine 80 mg/l, and hydrochlorothiazide 25 mg/l) and euthanized at 16 weeks after renal ablation. Treatments were started at 2 weeks (early treatment: Group I) or 8 weeks (later treatment: Group II) after the ablation. ACEI and AIIRA treatments were equally and significantly effective in limiting albuminuria and progression of glomerular sclerosis. TRX was also as effective in decreasing urinary albumin excretion and preserving the renal function as ACEI or AIIRA in Group I. The improvement of albuminuria, glomerular enlargement and sclerosis after these treatments in Group II was significantly less than that in Group I. It appears that the early treatment with angiotensin converting enzyme inhibitor, angiotensin II receptor antagonist or reserpine, hydralazine and hydrochlorothiazide (TRX) may prevent glomerular injury in human patients with renal hypertension.

Significance of urinary type IV collagen in patients with diabetic nephropathy using a highly sensitive one-step sandwich enzyme immunoassay

Urinary concentrations of type IV collagen in patients with diabetic nephropathy were measured by a highly sensitive, one-step sandwich enzyme immunoassay. Samples from 298 patients with noninsulin-dependent diabetes mellitus (NIDDM) and 80 healthy controls were examined. In diabetic patients with macroalbuminuria or renal insufficiency, the concentrations of urinary type IV collagen were significantly higher than those of diabetic patients with normoalbuminuria or healthy controls (P < 0.001). Urinary type IV collagen concentration in diabetic patients with microalbuminuria was significantly higher than that in diabetic patients with normoalbuminuria or that in healthy controls (P < 0.001). In contrast, there were no significant changes in the concentration of serum type IV collagen between microalbuminuric patients and normoalbuminuric patients. The area under the receiver operating characteristic (ROC) curve for the urinary type IV collagen concentration was equivalent to that of urinary albumin. It was concluded that urinary type IV collagen concentration determined using this method might be a useful marker for the early detection of diabetic nephropathy.

Enhanced expression of membrane type-1 matrix metalloproteinase in mesangial proliferative glomerulonephritis

Matrix metalloproteinase-2 (MMP-2, gelatinase A) is involved in the inflammatory and sclerotic events of glomerular diseases. Newly identified membrane-type matrix metalloproteinases (MT-MMP) have been shown to activate specifically proMMP-2. To date, several types of MT-MMP have been cloned; however, their expressions in glomerular diseases have not been evaluated. To investigate the role of MT-MMP in glomerular diseases, the glomerular gene expression and enzymatic activity of MT-MMP were examined during the time course of nephritis induced in rats by anti-Thy1.1 antibody injection. Both MT1-MMP and MMP-2 mRNA expression increased prominently 5 and 10 d after anti-Thy1.1 antibody injection and decreased thereafter, as assayed by semiquantitative reverse transcription-PCR. In contrast, there were no remarkable changes in the gene expression of MT2-MMP between normal and diseased tissue, and that of MT3-MMP was not detected in isolated glomeruli by reverse transcription-PCR analysis. The activation of proMMP-2 as analyzed by gelatin zymography correlated with the glomerular MT1-MMP gene expression, suggesting that proMMP-2 was activated by MT1-MMP. Protein and mRNA expression of fibronectin, one of the major mesangial matrix proteins and substrate of MMP-2, were also synchronized with MT1-MMP and MMP-2 expression. In situ hybridization revealed intense MT1-MMP mRNA expression in the proliferating mesangial cells. Interestingly, MT1-MMP gene expression exhibited a similar distribution as alpha-smooth muscle actin expression, which was closely associated with mesangial phenotypic change. These results suggest that among the newly identified MT-MMP, MT1-MMP may play the central role in activation of proMMP-2. Furthermore, the enhancement of MT1-MMP and MMP-2 expression associated with mesangial phenotypic change may contribute to the development of anti-Thy1.1 antibody-induced glomerulonephritis and remodeling of extracellular matrices.

Expression of cysteine proteinases and their inhibitor, cystatin beta, in cultured rat mesangial cells

Matrix expansion in the glomerular mesangial area is observed in diabetic nephropathy. Intracellular breakdown of long-lived proteins was lower in mesangial cells in the high glucose medium than that in the control medium. Enzymatic activity of cathepsin L increased 1.4-fold after 6 h of treatment with the high glucose, and then declined gradually to 72% of control cells after treatment for 36 h. Change in the enzyme activity of cathepsin B showed a similar time course but less magnitude than that of cathepsin L. Immunoblot analysis with anti-cathepsin L antibody showed that change in the enzyme activity of cathepsin L was due to the change in the amount of cathepsin L, and that with anti-cathepsin B antibody showed no change in the amount of cathepsin B in the mesangial cells treated with high glucose. Intracellular cathepsin activities were controlled not only by the amounts but also by the inhibitor cystatin beta. Immunoblot analysis with anti-cystatin beta antibody showed that intracellular levels of cystatin beta increased slightly after 24 h of treatment with high glucose. These changes were derived from changes in mRNA level. These results, therefore, demonstrated that the decrease of intracellular protein breakdown in mesangial cells treated with high glucose medium was due to both suppression of cathepsins and increase of cystatin beta.

Epstein-Barr virus detection in kidney biopsy specimens correlates with glomerular mesangial injury

To determine the relationship between the detection of Epstein-Barr virus (EBV)-specific DNA and glomerular injury, 33 renal needle-biopsy specimens that had been formalin-fixed and paraffin-embedded were analyzed using polymerase chain reaction (PCR) with subsequent nonradioactive Southern blot technique. Light microscopic examination and immunofluorescence were also performed. In 30 of 33 renal biopsy specimens, the beta globin gene could be successfully amplified as integrity controls. These 30 patients consisted of 12 patients with immunoglobulin A nephropathy (IgAN), 10 patients with minor glomerular abnormalities, 6 patients with membranous nephropathy, and 2 patients with focal/segmental lesions. EBV was detected in 7 of 12 patients with IgAN (58%), 3 of 6 patients with membranous nephropathy (50%), 0 of 10 patients with minor glomerular abnormalities (0%), and 2 of 2 patients with focal/segmental lesions. EBV detection was not disease specific. The EBV detection ratio of the group with glomerular mesangial lesions (64%; 9 of 14 patients) was significantly greater than those without (19%; 3 of 16 patients; P < 0.012, chi-square test). The EBV detection ratio of the group with glomerular lesions (60%; 12 of 20 patients) was significantly greater than those without (0%; 0 of 10 patients; P < 0.0016, Fisher's exact test), and the EBV detection ratio of the group with fibrinogen deposits observed in immunofluorescence (73%; 11 of 15 patients) was significantly greater than those without (7%; 1 of 15 patients; P < 0.0002, chi-square test). The EBV detection ratio of the group with immunoglobulin deposits (57%; 12 of 21 patients) was also significantly greater than those without (0%; 0 of 9 patients; P < 0.0040, Fisher's exact test). These data suggest that EBV can damage the glomerular mesangium beyond disease units and be mediated by immunoglobulin in patients with various chronic glomerulonephritides.

Dissociated expression of collagen type IV subchains in diabetic kidneys of KKAy mice

Diabetic nephropathy is characterized by thickening of the glomerular basement membrane and expansion of the mesangial matrix. The glomerular basement membrane is assembled from at least five genetically distinct collagen IV chains. In patients with diabetic nephropathy, differential distribution of these components has been demonstrated. In order to clarify the relationship between progression of diabetic nephropathy and altered type IV collagen assembly in the renal cortex, we examined steady state mRNA levels encoding collagen IV subchains in the kidney cortices of spontaneously diabetic KKAy mice and nondiabetic C57black mice as controls. They were sacrificed at 4, 8, 16, and 24 weeks of age. Northern and dot blot analyses were performed using 32P-labeled mouse probes for classical alpha1(IV) and alpha2(IV) and for alpha3(IV), alpha4(IV), and alpha5(IV) minor chains. The mRNA levels for all collagen IV chains peaked at 4 weeks of age and declined rapidly thereafter in the nondiabetic mice. At all times, alpha1(IV) and alpha2(IV) mRNA expressions were abundant and almost unchanged in KKAy mice. In contrast, mRNA levels for alpha3(IV), alpha4(IV), and alpha5(IV) progressively changed with age. It appears that the expression of minor collagen IV chains is dissociated from the alpha1(IV) and alpha2(IV) chains in diabetic nephropathy. Moreover, an unbalanced increase in the production may affect collagen IV assembly and contribute to basement membrane thickening in diabetic nephropathy of KKAy mice.

Multicentric Castleman's disease associated with renal amyloidosis and pure red cell aplasia

A 50-year-old man was admitted suffering from severe anemia and renal dysfunction. He had been admitted for the first time at the age of 49, and was diagnosed with multicentric Castleman's disease (MCD) and secondary amyloidosis. At that time, marked erythroid hypoplasia was demonstrated by both aspiration and biopsy of bone marrow. A diagnosis of pure red-cell aplasia (PRCA) was made. Immunosuppressive agents improved his symptoms and laboratory data. We report here a very rare case of PRCA following MCD and amyloidosis, and with reference to the literature, we discuss the relation between MCD and related diseases.

Distinct contribution of Fc receptors and angiotensin II-dependent pathways in anti-GBM glomerulonephritis

BACKGROUND

The contribution of antibody and/or immune-complex to the pathogenesis of immunologically-mediated glomerulonephritis is not fully understood, although it has been recently clarified that Fc receptors (FcRs) play critical roles in the inflammatory cascade. We therefore re-evaluated the classical model of glomerulonephritis, anti-glomerular basement membrane antibody-induced glomerulonephritis (Anti-GBM GN), from the standpoint of FcRs and also investigated the residual FcR-independent mechanisms.

METHODS

We adopted an Anti-GBM GN mouse model that has two strains deficient in the FcR gamma chain [gamma(-/-)] or Fc gammaRIIB [RII(-/-)], and analyzed functional (urinary protein, serum creatinine, BUN) and pathological changes of the glomeruli. For the analyses of FcR-independent mechanisms, several doses of nephrotoxic serum were applied, and then mice were treated either with cobra venom factor or an angiotensin II type 1 receptor antagonist in gamma(-/-) mice.

RESULTS

In gamma(-/-) mice, renal injuries were dramatically attenuated with an absence of polymorphonuclear cell (PMN) influx, while RII(-/-) mice suffered accelerated glomerular injuries in spite of a normal PMN influx. In the absence of FcR-dependent effects in gamma(-/-) mice, the FcR-independent pathway lead to chronic renal damage characterized by mesangial proliferation and progressive expansion of mesangial area, with monocyte/macrophage accumulation and with the expression of alpha smooth muscle actin in the mesangial cells and interstitium. Those injuries in gamma(-/-) mice were not attenuated by the decomplementation, but completely abolished by using an angiotensin II type 1 receptor antagonist.

CONCLUSIONS

Our results clearly demonstrate that FcRs play a pivotal role in Anti-GBM GN, especially in its acute phase. We further clarified the existence of FcR and complement-independent but antibody-dependent pathway. Furthermore, we found that those pathological changes were strongly related to the renin-angiotensin system.

Pharmacokinetics of cefdinir and its transfer to dialysate in patients with chronic renal failure undergoing continuous ambulatory peritoneal dialysis

Cefdinir (CAS 91832-40-5) was administered orally as a 100-mg capsule (Cefzon) to a total of 12 patients with chronic renal failure undergoing continuous ambulatory peritoneal dialysis (CAPD) to investigate changes in the serum concentrations, excretion rate into the dialysate and serum-protein binding of cefdinir. Cmax values were 1.64-4.34 micrograms/ml, t1/2 values were 10.8-21.9 h., and AUC values were 31.1-73.1 micrograms.h/ml (0-30 h) in four patients given a single oral dose of 100 mg of cefdinir as a capsule. About 1 microgram/ml of cefdinir had still remained in the blood of all the patients 24 h after administration. The serum concentrations of cefdinir were dose-dependent in four patients of each group who were given an oral daily dose of 100 mg for 3 to 8 days and 200 mg (2 capsules) for 4 to 14 consecutive days. No marked change in laboratory test values or clinical symptoms before and after administration were observed in these dose regimes. Protein levels of 5.17-5.71 g/day were eliminated from the peritoneal dialysate and urine. Cefdinir inhibited 90 to 100% of the clinical isolates such as Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and other enteric bacteria causing catheter infection and peritonitis, and its antibacterial activity was stronger than that of amoxicillin (CAS 26787-78-0) or cefaclor (CAS 53944-73-3) against these clinical isolates.

Mutations in CLCN5 chloride channel in Japanese patients with low molecular weight proteinuria

Mutations in the CLCN5 gene have been demonstrated in three disorders of hypercalciuric nephrolithiasis, i.e., Dent's disease, X-linked recessive nephrolithiasis, and X-linked recessive hypophosphatemic rickets. Recently, a number of Japanese children with low molecular weight proteinuria (LMWP) showing symptoms similar to those shown by patients with Dent's disease in British families have also been reported to have mutations in the CLCN5 gene. The present study examines five unrelated Japanese families with LMWP, two of which lacked any signs other than LMWP, and three of which had several signs other than LMWP, i.e., hypercalciuria, aminoaciduria, hypophosphatemia, and rickets. One nonsense (E118X) and one missense (W22G) mutation were found in three patients in the two families having only LMWP. One genomic deletion including exons 5 to 8 in the CLCN5 gene was found in a patient with hypophosphatemic rickets, and a nonsense mutation (R347X) was found in one patient with LMWP and slight hypercalciuria. No mutations of the exons and exon-intron boundaries in the CLCN5 gene were found in one patient with LMWP, aminoaciduria, and hypokalemia. In addition to the predicted loss of chloride channel function in these nonsense and deletion mutations, the loss of function in the missense mutation W22G was confirmed in the Xenopus oocyte expression system. These results clarified four novel mutations in the CLCN5 genes, and additionally suggested that the loss-of-function mutation of the CLCN5 does not necessarily lead to hypercalciuria and nephrocalcinosis in the early stage of the disease, and that LMWP is an early and essential manifestation of disorders of the CLC-5 chloride channel.

Effects of the antihypertensive drug efonidipine hydrochloride on albuminuria and renal histopathology in young spontaneously hypertensive rats with diabetes

1. We investigated the renal protective effect of efonidipine hydrochloride (efonidipine, NZ-105) in STZ-induced spontaneously hypertensive rats (SHRs, 8 weeks of age). Diabetic SHRs were treated with 15 mg/kg/day of efonidipine for 12 weeks. 2. The dosage of efonidipine was chosen after preliminary studies demonstrated that it showed mild antihypertensive action (within 20% decrease of systemic blood pressure). 3. In the diabetic SHRs, the excretion of urinary albumin was increased (1.78 +/- 0.09 mg/day) at 4 weeks and reached 4.41 +/- 0.12 mg/day at 12 weeks. The levels of urinary albumin in the diabetic SHRs after treatment with efonidipine were significantly less than those in the diabetic SHRs at 8 and 12 weeks (P < 0.01). 4. Levels of creatinine clearance were decreased in the diabetic SHRs after treatment with efonidipine. 5. In light microscopy, the ratio of glomerular tuft to Bowman's areas was significantly decreased compared with those in the diabetic SHRs (P < 0.05). 6. These findings suggest that efonidipine inhibits the development of albuminuria and glomerular enlargement in the streptozotocin-induced diabetic SHRs and may become a useful antihypertensive drug with a renal protective effect.

Effects of antihypertensive drugs on antioxidant enzyme activities and renal function in stroke-prone spontaneously hypertensive rats

The reactive oxygen species has been proposed as a key mediator of the progression of renal injury associated with essential hypertension. Among the defense systems operating against the reactive oxygen species, superoxide dismutase, glutathione peroxidase, and catalase are the most important antioxidant enzymes (AOEs). In the present study, systolic blood pressure, renal function (creatinine clearance, urinary albumin, and N-acetyl-beta D-glucosaminidase excretion), renal intrinsic AOE activities, and renal histopathology were determined in stroke-prone spontaneously hypertensive rats and Wistar Kyoto rats. The effects of a 20-week treatment using three antihypertensive drug regimens--captopril, a sulfhydryl-containing angiotensin-converting enzyme inhibitor; temocapril, a potent, non-sulfhydryl-containing angiotensin-converting enzyme inhibitor prodrug; and a conventional triple drug combination that includes a vasodilator (hydralazine, hydrochlorothiazide and reserpine)--on renal function, renal tissue, AOE activities, and renal histopathologic abnormalities were evaluated in stroke-prone spontaneously hypertensive rats. Renal function and AOE activities were lower in the stroke-prone spontaneously hypertensive rats than in the Wistar Kyoto rats. Normalization of systolic blood pressure using the antihypertensive drugs improved renal function and produced a nonuniform alteration in renal AOEs; only glutathione peroxidase activity increased significantly with the use of all three drug regimens. The mild renal histopathologic abnormality in stroke-prone spontaneously hypertensive rats was not altered by drug treatment. The improvement in renal function may be related to an increase in glutathione peroxidase activity, but no correlation was seen between renal function changes and alteration in activities of superoxide dismutase or catalase.

Increased endothelin-1 mRNA expression in peripheral blood monocytes of dialysis patients

OBJECTIVE

To compare plasma endothelin (ET)-1 level and ET-1 mRNA level in peripheral blood monocytes of patients undergoing hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD).

DESIGN

Endothelin-1 mRNA level in peripheral blood monocytes and plasma ET-1 level were studied in 30 HD patients, 15 CAPD patients, 20 chronic renal failure patients not being dialyzed, and 20 normal healthy controls. Hemodialysis patients were dialyzed three times per week with a bicarbonate dialysate. Different types of dialyzer membrane, viz., cellulose triacetate, cuprophane, polysulfone, polyacrylonitrile, and ethylenevinylalcohol were used in 8, 6, 6, 5, and 5 patients, respectively. Continuous ambulatory peritoneal dialysis patients were dialyzed with four daily exchanges of a 2-L dialysate containing glucose at a concentration of 1.5% to 2.5%.

RESULTS

Higher levels of ET-1 mRNA in monocytes were observed in HD patients than in CAPD patients (p < 0.01), chronic renal failure patients (p < 0.01), or normal healthy controls (p < 0.001). The level of ET-1 mRNA in monocytes at the end of HD was not significantly higher than that at the start of HD. In addition, these mRNA levels in HD patients showed little difference with different types of dialysis membrane. Plasma ET-1 level in HD patients (10.2 +/- 2.4 pg/mL) was also higher than that in CAPD patients (7.8 +/- 1.6 pg/mL, p < 0.01), in chronic renal failure patients (4.8 +/- 1.2 pg/mL, p < 0.01), or in normal controls (2.6 +/- 0.8 pg/mL, p < 0.001).

CONCLUSION

Dialysis itself did not significantly affect ET-1 mRNA levels in monocytes. Chronic stimulation of peripheral blood monocytes may be associated with higher levels of ET-1 mRNA and plasma ET-1 in HD patients than in CAPD patients.

A case of lupus nephritis showing good clinical course and apoptosis in glomerular cells detected by the nick end labeling method

We report here an adult patient with lupus nephritis who had a good clinical course under long-term observation. Apoptotic bodies in the glomeruli were determined in serial renal biopsy specimens by the nick end labeling method. Apoptotic bodies in the proliferated glomerular cells were detected in the 3rd renal biopsy but not in the 2nd biopsy. The clinical activities of lupus nephritis fluctuated until the time of the 3rd renal biopsy. The 3rd renal biopsy was performed because of increased proteinuria and an increased amount of hyaline, granular and red blood cell casts, with impairment of renal function. The levels of proteinuria, creatinine clearance and serum complements were improved after the 3rd renal biopsy. It appears that apoptosis might control glomerular cell proliferation and also influence the clinical course of lupus nephritis.

Effect of a specific endothelin receptor A antagonist and an angiotensin-converting enzyme inhibitor on glomerular mRNA levels for extracellular matrix components, metalloproteinases (MMP) and a tissue inhibitor of MMP in aminonucleoside nephrosis

BACKGROUND

We previously reported that mRNA levels for extracellular matrix (ECM) components and endothelin (ET)-1 are upregulated in glomeruli of puromycin aminonucleoside (PAN) nephrosis. Angiotensin-converting enzyme (ACE) inhibitors are effective in experimental models of renal injury, including PAN nephrosis. This study was designed to assess whether the glomerular expression of mRNA for ECM components, ET-1, metalloproteinases (MMP), and a tissue inhibitor of metalloproteinases (TIMP) is modulated by a specific endothelin receptor A antagonist (FR139317) or angiotensin-converting enzyme inhibitor (enalapril) in PAN-injected rats.

METHODS

Animals were divided into six groups. Group 1 consisted of PAN-injected rats given no treatment. In group 2, PAN-injected rats were given enalapril 35 mg/l. In group 3, PAN-injected rats were given an intraperitoneal injection of FR139317. Group 4 consisted of saline-injected rats given no treatment. In group 5, saline-injected rats were given enalapril. In group 6, saline-injected rats were given FR139317. We prepared glomerular RNA and performed Northern blot analysis in all groups.

RESULTS

In PAN nephrosis, glomerular mRNA levels for alpha 1 (IV) collagen chain, laminin B1 and B2 chains, ET-1, MMP-2 and TIMP-1 increased at the peak of proteinuria on day 8 and then decreased to the control level by day 20, whereas those for alpha 1 (I) and alpha 1 (III) collagen chains, MMP-1, MMP-3 and GAPDH showed little change in PAN nephrosis throughout the experimental periods. In contrast, mRNA levels for heparan sulphate proteoglycan (HSPG) decreased on day 8 and then increased to the control level by day 20. Both enalapril and FR139317 attenuated the increases in mRNA levels for alpha 1 (IV) collagen chain (P < 0.01), laminin chains (P < 0.01), and ET-1 (P < 0.01), and attenuated the decreases in mRNA levels for HSPG (P < 0.01) in glomeruli of PAN-injected rats. Enalapril had little effect on increased glomerular mRNA levels for MMP-2 and TIMP-1 in PAN nephrosis, whereas FR139317 attenuated the increases in glomerular mRNA levels for MMP-2 (P < 0.01) and TIMP-1 (P < 0.01).

CONCLUSIONS

These data suggest that the beneficial effects of enalapril and FR139317 may be related to modulation of glomerular mRNA expression of ECM components and ET-1 and that these agents may follow a different mechanism in regulating the glomerular mRNA expression for MMP-2 and TIMP-1 in PAN nephrosis.

Association of alexithymia with low utilization and perception on a measure of social support in patients on peritoneal dialysis

This study examined the association of social support and alexithymia in 63 patients with end-stage renal failure on peritoneal dialysis. Scores on the Toronto Alexithymia Scale were significantly higher for the patient group than the control group. Social support was measured with the Stress and Coping Inventory. For scores on the Existence of social support there was no significant difference between the two groups; however, scores on the Utilization and Perception of social support were significantly lower for the patients than for the control group. The alexithymia scores were significantly and negatively correlated with the scores on the Utilization and Perception of social support. Our findings suggest that patients with peritoneal dialysis score higher on a measure of alexithymia associated with low utilization and perception of social support.

Effects of benidipine hydrochloride on antioxidant enzyme activity in stroke-prone spontaneous hypertensive rats (SHR-SP)

Effects of benidipine hydrochloride or triple therapy (hydralazine, reserpine, and hydrochlorothiazide) on renal cortical and medullary intrinsic antioxidant enzyme (AOE) activity were evaluated in stroke-prone spontaneously hypertensive rats (SHR-SP) as an animal model for human essential hypertension with cerebral stroke. This study showed a significant decrease of renal intrinsic glutathione peroxidase (GSH-Px) activity in untreated SHR-SP. Renal GSH-Px activity in untreated SHR-SP was significantly lower than that in Wister Kyoto rats (WKY) as a normotensive reference strain. GSH-Px activity in SHR-SP was significantly improved after benidipine hydrochloride therapy. Levels of urinary albumin excretion or creatinine clearance (Ccr) in SHR-SP were also improved after the therapy. Glomerular sclerosis index was slightly improved in SHR-SP treated with benidipine hydrochloride according to light microscopic analysis. It appears that hypertension may influence the renal intrinsic GSH-Px activity, albuminuria, and Ccr in SHR-SP. Thus it is indicated that control of blood pressure may improve the GSH-Px activity in SHR-SP.

Effect of unilateral nephrectomy on gene expression of metalloproteinases and their inhibitors

Levels of mRNA encoding for metalloproteinase (MMP) 1, 2, 3 and 9 and tissue inhibitor of metalloproteinase (TIMP) 1 were measured in both the renal cortex and glomeruli following unilateral nephrectomy or a sham operation. The expression of MMP-1 and MMP-3 increased 3-fold (p < 0.001) within the renal cortex 24 h following nephrectomy, and then gradually decreased to the control level after 7 days. In contrast, expression of MMP-2 and MMP-9 remained unchanged following nephrectomy. TIMP-1 mRNA levels also significantly increased 4-fold (p < 0.001) within the renal cortex 12 h following nephrectomy, followed by a decrease to the control level after 3 days. In contrast, the glomerular expression of MMP-1, -2, -3 and TIMP-1 remained stable while minimal MMP-9 mRNA was detectable. MMPs and TIMP-1 may be associated with the early stages of renal hypertrophy following unilateral nephrectomy.

Effects of antihypertensive drugs or glycemic control on antioxidant enzyme activities in spontaneously hypertensive rats with diabetes

The activities of glomerular intrinsic antioxidant enzymes (AOEs) were measured in a diabetic spontaneously hypertensive rat (SHR) model. The effects of antihypertensive drugs, i.e. captopril or triple therapy (hydralazine, reserpine, and hydrochlorothiazide), on glomerular intrinsic AOE activities in this model were evaluated. The effects of blood glucose control on the AOE activities were also determined. The aim of the present study was to determine whether activities of glomerular intrinsic AOEs might correlate with disease activity in diabetic SHR. This study showed a decrease of glomerular intrinsic AOE, i.e. Cu/Zn-SOD and Mn-SOD (SOD = superoxide dismutase), glutathione peroxidase, and catalase, activities in diabetic SHR. Glomerular Cu/Zn-SOD or Mn-SOD, glutathione peroxidase, and catalase activities in nondiabetic SHR were slightly lower than those in nondiabetic WKY rats. These activities in diabetic SHR were significantly improved after captopril or triple therapy or blood glucose control. The levels of urinary albumin excretion, creatinine clearance, and glomerular tuft areas in diabetic SHR were also improved after the therapy. It appears that hypertension and hyperglycemia may influence the glomerular intrinsic AOE activities, albuminuria, creatinine clearance, and glomerular tuft areas in diabetic SHR. Thus, it is indicated that control of blood pressure or blood glucose is a very important factor for preventing renal injuries in the diabetic SHR model.

Effects of endothelin 1 on phosphate transport in brush border membrane vesicles

Endothelin is the most potent vasoconstrictive agent released from endothelial and many other types of cells. It has been reported that endothelin has physiological effects on the rat kidney, especially on the renal proximal tubules. We investigated the role of endothelin 1 in the renal brush border membrane. The V(max) of P(i) uptake by brush border membrane vesicles (BBMV) in the endothelin-1-treated group was significantly greater than that in the control group. There were no significant changes in apparent K(m) values between the two groups. To define the direct effect of endothelin 1 on P(i) transport of BBMV, BBMV from normal rats were incubated with endothelin 1 in vitro. The P(i) uptake by BBMV incubated with endothelin 1 did not differ from that by BBMV incubated with a salt solution as a control. These results suggested the probability of the presence of endothelin 1 receptor in the proximal tubules. Administration of the endothelin 1 might increase the P(i) reabsorption by BBMV according to changes in the capacity of the transporter.

The development of focal segmental glomerulosclerosis in masugi nephritis is based on progressive podocyte damage

We analysed the sequence of structural changes leading to focal segmental glomerulosclerosis (FSGS) in chronic Masugi nephritis. The protocol resulted in an immediate onset of the disease and the development of segmental sclerosis in a considerable proportion of glomeruli within 28 days of serum injection. Throughout the study, the degree of structural damage was significantly correlated with protein excretion. Even 1 day after injection of the serum, the whole spectrum of early lesions was encountered involving all three cell types. Endothelial detachments, mesangiolysis and podocyte foot process effacement were most prominent. There was focal persistence of capillary microthrombosis but, generally, mesangial and endothelial injuries recovered. The development of podocyte lesions was different: on one hand recovery was seen leading to the re-establishment of an interdigitating foot process pattern, and on the other persistent podocyte detachments from peripheral capillaries allowed the attachment of parietal epithelial cells to "naked" portions of the glomerular basement membrane (GBM), and thus to the formation of a tuft adhesion to Bowman's capsule. Progressive podocyte degeneration at the flanks of an adhesion permitted expansion of the adhesion by encroachment of parietal cells onto the tuft along the denuded GBM. Inside an adhesion, capillaries and mesangial areas either collapse or become obstructed by hyalinosis or thrombosis. Resident cells disappear progressively from inside an adhesion; macrophages may invade. Segmental sclerosis in this model consists of collapsed tuft structures adhering broadly to the cortical interstitium. Proliferation of mesangial cells did not contribute to this development. Recovery of endothelial and mesangial lesions was associated with cell proliferation in early stages of the disease; podocyte proliferation was not encountered at any stage. We conclude that the inability to replace an outmatched podocyte crucially underlies the development of sclerosis. Severe podocyte damage cannot be repaired but leads to tuft adhesions to Bowman's capsule followed by progressive collapse of tuft structures inside an adhesion, resulting in segmental glomerulosclerosis.

Early induction of the NGFI-B/Nur77 family genes in nephritis induced by anti-glomerular basement membrane antibody

We recently isolated a novel nuclear receptor NOR-1, which is a member of the steroid/thyroid receptor superfamily, and belongs to the NGFI-B/Nur77 family. In the present study, we examined gene expression of NOR-1 and its closely related members in nephritis induced by anti-glomerular basement membrane (GBM) antibody. The mRNA levels for NOR-1, NGFI-B and RNR-1 increased 24 h after injection of anti-GBM antibody (day 1). Gene expression of NOR-1 and NGFI-B reached maximum levels on day 3, gradually decreased thereafter and returned to control levels on day 28. RNR-1 reached a peak on day 7, and then decreased. Renal injuries were most prominent on day 7 and persisted until day 28, indicating that NOR-1, NGFI-B and RNR-1 genes are induced during the early stage of glomerulonephritis and may be associated with the progression of glomerulonephritis. The induction of the NGFI-B gene was less remarkable than that of NOR-1 and RNR-1. In addition, administration of glucocorticoid hormone suppressed NOR-1 and RNR-1 gene expression to almost normal levels, whereas NGFI-B gene expression was not significantly repressed. These findings also suggest that the NGFI-B/Nur77 family may possess different biological roles and NGFI-B might act as a general transcription factor in cell function.

A case of reflex anuria and uremia related to a unilateral ureteral stone

A 63-year-old man had anuria associated with a unilateral ureteral stone for 24 hours. Laboratory data indicated marked azotemia with the serum creatinine concentration of 7.2 mg/dL and urea nitrogen of 48 mg/dL. The radiological findings revealed contralateral hydronephrosis. Spontaneous discharge of the ureteral stone reversed the anuria and uremia. Both ureteral and vascular spasms were attributed to the anuria in this patient.

Re-evaluation of foot process effacement in acute puromycin aminonucleoside nephrosis

The sequence of morphological changes during foot process effacement in acute puromycin aminonucleoside (PAN) nephrosis was examined by means of NaOH maceration and freeze cracking for scanning electron microscopy (SEM). The micrographs of SEM and those of transmission electron microscopy (TEM) were quantitatively analyzed by computerized morphometry, and were correlated with renal function. On day 2 after PAN injection, the slit length was moderately decreased by both shortening and degradation of the foot processes. On day 4, membrane-bounded vesicles were scattered in the lamina rara externa. During foot process effacement, the basal surface of podocytes developed palm-like domains that represented the cytoplasmic areas between interdigitation. The decrease in the length of podocyte cell borders paralleled the decrease of 24-hour creatinine clearance. The development of the palm-like domains on the basal aspects of podocytes estimated by distance class analysis was closely correlated with the sudden onset of proteinuria. We conclude that foot process effacement in PAN nephrosis caused by the retraction and degradation of foot processes leads to the development of palm-like domains, which is correlated with podocyte detachment as well as massive proteinuria.

Effect of probucol on mRNA expression of glomerular antioxidant enzymes in rat with subtotal nephrectomy

OBJECTIVE

To investigate 1) the glomerular mRNA expression and protein activity of antioxidant enzymes (AOEs) including superoxide dismutase (SOD) and glutathine peroxidase (GSH-Px) and the glomerular content of lipid peroxide-malondiadehyde (MDA), 2) the effects of probucol (P), a potent antioxidant agent on these AOEs and MDA levels, in the chronic phase of subtotal nephrectomized rats.

METHODS

The adult male Spregue-Dawley rats were randomly divided into three groups at the first week after subtotal renal ablation. Group 1 was sham rats (sham n = 8), group 2 underwent 5/6 nephrectomy without special therapy (5/6 Nx n = 8), and group 3 with 5/6 nephrectomy received probucol (5/6 Nxs+P n = 8) at a dose of 1% in the rat chow. At the 12th week after P was administrated, all of the rats were sacrificed to remove left kidney for the determination of glomerular level of MDA, activity of SOD, and GSH-Px, glomerular mRNA expression of AOEs by Northern blot analysis as well as a histological examination.

RESULTS

In 5/6 Nx, serum cholesterol, proteinuria increased and creatinine clearance decreased progressively with age as compared with that in sham. Those abnormalities as well as glomerulosclerosis index (GI) ameliorated with the administration of probucol at the 12th week after subtotal nephrectomy [GI: sham 3.12 +/- 1.20, P < 0.01 vs 5/6 Nx 5/6 Nx 188.6 +/- 25.1; 5/6 Nx +/- P, 106.9 +/- 17.6, P < 0.05 vs 5/6 Nx]. The probucol therapy also significantly improved the decrease of glomerular Mn-SOD and GSH-Px both at mRNA level and protein activity and the increase of glomerular MDA content.

CONCLUSIONS

We demonstrated a deficiency of glomerular AOEs in the chronic phase of remnant kidney, which may contribute to the progression of renal injury. The protective effects of probucol on both renal functional impairment and the development of glomerulosclerosis may be partially associated with improving surviving glomerular AOEs.

Effect of a low-protein diet on expression of non-muscle type myosin heavy-chain isoforms in glomeruli of rats with puromycin aminonucleoside nephrosis

BACKGROUND

We reported that an embryonic type of non-muscle-type myosin heavy-chain isoform (SMemb) may be a molecular marker for phenotypic alteration in initial glomerular injury and that methyl-prednisolone has no effect on SMemb expression in glomeruli of rats with puromycin aminonucleoside (PAN) nephrosis. The present study was designed to assess whether SMemb mRNA and protein expression in glomeruli are affected by a low-protein diet in rats with PAN-induced nephrosis and in control rats.

METHODS

Rats were divided into four groups: group 1, PAN-injected rats fed a standard diet containing 22% protein; group 2, PAN-injected rats fed a low-protein diet containing 6% protein, starting on the day of PAN injection; group 3, control rats fed a standard diet; group 4, control rats fed a low-protein diet for the same period. We prepared glomerular RNA and performed Northern blot analysis and immunohistochemistry in all groups.

RESULTS

Glomerular SMemb mRNA increased on days 2 and 4 (prior to and soon after the onset of proteinuria), but declined on day 8 (the peak of proteinuria). Myosin heavy-chain protein expression was evaluated immunohistochemically by use of three antibodies against SM1, SM2, and SMemb. SM1 and SM2 were absent from the glomeruli of rats with PAN nephrosis until day 20. The SMemb isoform was barely detectable in normal glomeruli, but substantial amounts of SMemb were demonstrated in the glomeruli of rats with PAN nephrosis. In the latter condition, the number of SMemb-positive glomerular epithelial cells increased on days 3 and 4, then decreased in subsequent days. Moreover, some mesangial cells became SMemb-positive transiently, returning to barely detectable levels on day 20. In addition, alpha-smooth-muscle actin, type I and III collagens were absent from the glomeruli of rats with PAN nephrosis until day 20. Urinary protein excretion was markedly suppressed by the 6% protein diet in PAN nephrosis. The low-protein diet reduced the increased mRNA expression of SMemb as well as the increased number of SMemb-positive cells in the glomeruli of rats with PAN nephrosis. However, the low-protein diet did not affect SMemb mRNA and protein levels in the glomeruli of control rats.

CONCLUSIONS

In rats with PAN nephrosis, findings suggest that restriction of dietary protein leads to a reduction in glomerular SMemb expression.

Alteration of growth-related proto-oncogene expression in diabetic glomeruli by a specific endothelin receptor A antagonist

BACKGROUND

The early phase of glomerular growth in diabetic rats is accompanied by increased c-fos and c-jun expression. The renal endothelin (ET)-1 mRNA levels increased with the progression of diabetic nephropathy. This study was designed to assess whether glomerular mRNA expression of growth-related proto-oncogenes in diabetic rat glomeruli is affected by a specific ET receptor A antagonist, FR139317.

METHODS

Diabetes was produced by streptozotocin (STZ) injection. Animals were divided into four groups: (1) untreated diabetic rats (n = 25); (2) FR139317-treated diabetic rats (n = 20); (3) control non-diabetic rats (n = 20); and (4) FR139317-treated controls (n = 20). FR139317 treatment was continued for 24 weeks. c-myc, c-fos, c-jun and proliferating cell nuclear antigen (PCNA) mRNA expression in rat glomeruli from each group (n = 7) at 4, 12 and 24 weeks after STZ or saline injection was evaluated.

RESULTS

Glomerular mRNA levels for c-myc, c-fos, c-jun and PCNA in group 1 increased with the progression of diabetic nephropathy (24 weeks: c-myc, 4.6-fold; c-fos, 3.8-fold; c-jun, 4.2-fold; and PCNA, 4.4-fold). FR139317 treatment attenuated increases in glomerular mRNA levels of these genes (24 weeks, c-myc, 0.4-fold; c-fos, 0.4-fold; c-jun, 0.5-fold; and PCNA, 0.4-fold) in group 2. However, FR139317 did not affect mRNA levels in control glomeruli.

CONCLUSIONS

These data suggest that FR139317 may protect against glomerular injury of diabetes in rats by reducing mRNA levels of growth-related genes.

Three-dimensional analysis of the whole mesangium in the rat

The three-dimensional structure of the mesangium was analyzed by means of reconstruction from serial semithin and ultrathin sections of the rat glomerulus. The mesangial domains traced on light micrographs of semithin sections were transferred to styrene models, which were stacked up to reconstruct the whole mesangium. The reconstructed mesangium was tree-like in shape and was divided into three lobes that were connected to the vascular pole by a slender neck. The glomerulus contained no islets of mesangium which were not connected to the vascular pole. The mesangium contained 64 mesangial loops that were penetrated by capillaries. Reliability of the findings on the mesangial loops was ascertained by various methods including reconstruction of part of the mesangium from ultrathin sections. Electron microscopic observations revealed that the arms of the mesangial loops were frequently very slender and consisted of mesangial cell processes containing prominent bundles of actin filaments. The mesangial loops were distributed evenly within the mesangium. Considering previous reports showing about 400 capillary branches in the rat glomerulus as well as the present findings, we concluded that the mesangial loops may change the distribution of intraglomerular blood flow by dynamic contraction of the mesangial cells, or serve as an additional safety device to prevent the expansion of glomerular capillaries.

[Serum levels of remnant-like particles-cholesterol (RLP-C) in patients on hemodialysis]

Serum remnant-like particles-cholesterol (RLP-C), an atherosclerosis risk factor that strongly reflects disorders of chyromicron and VLDL metabolism and contains high levels of TG, was measured in patients on hemodialysis and CAPD. The purpose of this study was to determine the serum levels of RLP-C in 30 outpatients on hemodialysis (18 males, 12 females) and 84 patients on CAPD (53 males, 31 females). The serum RLP-C level was 8.1 +/- 13 mg/dl in CAPD patients and 2.7 +/- 0.2 mg/dl in hemodialysis patients (p < 0.001). Patients who used dialysate containing over 150 g of glucose per day, showed higher levels of serum RLP-C than CAPD patients whose glucose consumption was under 150 g (10.4 +/- 2.4 mg/dl vs. 5.5 +/- 0.6 mg/dl, p < 0.01). There was no statistical relationship between age, sex, dialysis duration and serum RLP-C in CAPD and hemodialysis patients. Serum level of RLP-C was positively correlated with serum triglyceride, total cholesterol, apolipoprotein B and VLDL, and was negatively correlated with apoA-I/apoB in the dialysis patients. It appears that RLP-C, which is one of the risk factors of atherosclerosis, might reflect a disorder of triglyceride metabolism in patients on dialysis, especially on CAPD.

Case report: late relapse in a case of mesangioproliferative glomerulonephritis

A case of atypical proliferative glomerulonephritis (PGN) without mesangial immunoglobulin (Ig) A deposition (so-called non-IgA PGN) showing exacerbation of heavy proteinuria under long-term observation is reported. Examinations of first renal biopsy specimens revealed membranoproliferative glomerulonephritis (MPGN)-like findings. Urinary protein excretion completely disappeared after treatment with prednisolone (PSL) and an antiplatelet drug, i.e., dipyridamole. Negative reaction for urinary protein continued for more than 10 years. Fourteen and a half years after the first biopsy, the patient had heavy proteinuria again. Results of the second renal biopsy showed marked proliferation of glomerular mesangial cells. Under electron microscopy, lobulation and double contours of the glomerular capillary walls were also observed segmentally. Depositions of IgG, IgM, IgA, and C3 were observed mainly in the glomerular capillary walls, but not in the mesangial areas; however, these findings were not compatible with IgA nephropathy or MPGN. No hypocomplementemia was observed during the clinical course. The patient was treated with 30 mg of PSL and 75 mg of dipyridamole daily and showed a good response to such treatment. It appears that this patient had a rare case of atypical non-IgA PGN.

Increased mRNA expression of metalloproteinase-9 in peripheral blood monocytes from patients with immunoglobulin A nephropathy

We examined metalloproteinase (MMP)-1, -2, -3, and -9 mRNA expression by peripheral blood monocytes from 50 patients with immunoglobulin A (IgA) nephropathy, 20 with membranous nephropathy, 10 with minimal-change nephrotic syndrome, five with focal glomerulosclerosis, 30 with non-IgA proliferative glomerulonephritis, and 40 healthy normal controls who were comparable with regard to age and sex. Monocytes from patients with IgA nephropathy expressed a higher level of MMP-9 mRNA than those from patients with other forms of glomerulonephritis or from healthy controls (MMP-9 to glyceraldehyde-3-phosphate dehydrogenase ratio: IgA nephropathy, 1.68 +/- 0.24; membranous nephropathy, 0.22 +/- 0.08; minimal-change nephrotic syndrome, 0.24 +/- 0.06; focal glomerulosclerosis, 0.32 +/- 0.08; non-IgA proliferative glomerulonephritis, 0.30 +/- 0.12; and healthy controls, 0.16 +/- 0.04). When the biopsy specimens were classified into four grades according to the severity of glomerular and interstitial pathology, highly significant differences were observed among MMP-9 mRNA levels in monocytes from all four groups of patients with IgA nephropathy (grade I, 0.44 +/- 0.09; grade II, 1.06 +/- 0.26; grade III, 2.22 +/- 0.68; grade IV, 2.86 +/- 0.88). In addition, MMP-9 mRNA levels from patients with IgA nephropathy correlated with urinary protein excretion (P < 0.001). However, we detected minimal mRNA expression of MMP-1, -2, and -3 by peripheral blood monocytes from patients with IgA nephropathy or other forms of glomerulonephritis and from normal healthy controls. Our results suggest that increased MMP-9 mRNA expression in circulating monocytes may contribute to the progression of IgA nephropathy.

Cytoskeletal changes in podocytes associated with foot process effacement in Masugi nephritis

Foot process effacement represents the most characteristic change in podocyte phenotype under a great variety of experimental as well as human glomerulopathies. It consists in simplification up to a total disappearance of an interdigitating foot process pattern. Finally, podocytes affix to the glomerular basement membrane by outspread epithelial sheets. Structural and immunocytochemical techniques were applied to analyze the cytoskeletal changes associated with foot process effacement in Masugi nephritis. Three days after injection of the anti-glomerular-basement-membrane serum an interdigitating foot process pattern was almost fully lost; more than 90 percent of the outer glomerular capillary surface were covered by expanded sheets of podocyte epithelium that contain a highly organized cytoskeleton adhering to the basal cell membrane. Structurally, this cytoskeleton consists of an interwoven network of microfilaments with regularly distributed dense bodies, which obviously serve as cross-linkers within this network. Immunocytochemically, the expression of actin, alpha-actinin, and pp44 (a specific podocyte protein normally associated with the cytoskeleton of foot processes) were increased in this structure; alpha-actinin was especially prominent in the dense bodies. The results are consistent with the view that foot process effacement represents an adaptive change in cell shape including hypertrophy of the contractile apparatus, reinforcing the supportive role of podocytes. Several factors associated with increased distending forces to podocytes may underlie this phenotype change including loss of mesangial support, elevated glomerular pressures, and impairment of GBM substructure as well as of podocyte-GBM-contacts. Twenty-eight days after serum injection a remodeling of the foot process pattern was seen. It appears that this restitution depends on a preceding repair of mesangial support function to glomerular capillaries.